The present invention relates to an amplitude range classifier for classifying amplitudes of an analog signal into one or more subranges of a larger range according to value of that amplitude.
Communication channels can be entirely analog extending from the information source to the transmitter, and then along the channel link to the receiver, and finally to the user of the transmitted information. Communication channels can also be digitally based, either totally or partially. A typical situation is to have a digital information source but where the information is sent in analog form over an analog channel link to a receiver which reconverts the information to a digital format.
In digitally based communications channels the amplitude of incoming baseband analog signals often contains the information carried by the signal. Thus, extracting information from the signal through knowledge of signal amplitudes at various times must be accomplished.
Amplitude range classifiers operate by dividing the range into which incoming signal amplitudes may fall into various subranges. Comparators may then be used to determine the subrange or subranges into which the amplitude of a particular data sample from the incoming baseband analog signal fits. The various comparators should operate in effect at the same time to ensure that a single value for each data sample from the incoming baseband analog signal is presented to each comparator for comparison with subrange boundary reference signals.
Conceptually, the function performed by the amplitude range classifier system could be performed by the use of an analog-to-digital converter which would supply digitized data samples at the output thereof to a series of digital comparators. However, at the very high baud rates at which digitally based communications channels often operate, there is not sufficient time for the currently available analog-to-digital converters to converge on a value for one data sample before the next data sample is to be taken.
Again conceptually, the monitor system could function satisfactorily with analog comparators in the amplitude range classifier all being connected directly to the incoming baseband analog signal if the time delays in each of the comparators and associated circuitry were either negligible or essentially identical. However, if there are delays and they are unequal, the effect is equivalent to having each of the comparators sampling at different times even if they are all controlled by a single clock.